Are variations in the geomagnetic field somehow associated with earthquakes or vice versa?
The USGS supports an important National Earthquake Hazards Program. As a small part of that effort there have been studies attempting to correlate magnetic variations, or more precisely, electro-magnetic variations, with earthquakes. Electromagnetic variations have been observed after earthquakes for many years now, but What is less clear is whether or not there are detectable electro-magnetic precursors to earthquakes. It is worth acknowledging that geophysicists would actually dearly love to demonstrate the reality of such precursors, especially if they could be used for reliably predicting earthquakes! Unfortunately, no convincing evidence of electro-magnetic precursors to earthquakes has been found, despite decades of work. And it should be emphasized that isolated coincidences are not sufficient to demonstrate a relationship. What is needed to confirm an extraordinary claim is, of course, an extraordinary amount of evidence, which in this case would mean many repeated correlations
